JP5206339B2 - Position shift amount detection device, position shift amount detection method, position shift amount detection program - Google Patents

Description

  The present invention relates to an apparatus for detecting a misregistration amount associated with each image of a plurality of colors when obtaining a visualized image by superimposing a plurality of colors in a tandem image forming apparatus.

  A so-called tandem image forming apparatus uses different image forming means for all four colors, and forms a color image by superimposing a toner image directly on paper or on an intermediate transfer belt.

  In such a tandem type image forming apparatus, the position where the images of the respective colors are superimposed is slightly shifted, so that a stable color image cannot be obtained. For this reason, misregistration correction is generally performed in which a misregistration correction mark is formed for each color, the image position of each color is detected by a detection unit, and all four colors are superimposed on the same position (Patent Document 1). In general, the detection result of the color mark (cyan, magenta, yellow) and the detection result of the reference color mark (black) are compared, and the positional deviation amount of the color mark with respect to the reference color mark is calculated.

Here, the detection means (sensor) is composed of a light emitting portion and a light receiving portion, and irradiation light is emitted from the light emitting portion to a misalignment correction mark formed on the conveyor belt, and the reflected light is received by the light receiving portion. By doing so, a misalignment correction mark is detected.
JP 2003-266798 A

  On the other hand, the reflected light detected by the detecting means includes a regular reflected light component and a diffuse reflected light component. Regularly reflected light is strongly reflected on the conveyor belt and absorbed on the toner image, and diffusely reflected light is weakly reflected on the color mark toner image and is reflected on the conveyor belt and on the black toner image. Then it is absorbed.

  Therefore, when a toner image of a color mark is detected using a conventional detection method, detection is performed from reflected light in which specular reflection light and diffuse reflection light are mixed. When the external and internal functions, or the adjustment of these individual positional relationships) are deviated due to mechanical tolerances, assembly errors, etc., the peak position of specularly reflected light and the peak position of diffusely reflected light do not match. As a result, there is a problem that an error occurs in the detection position of the color mark.

  Accordingly, in the present invention, in view of the above problems, a positional deviation amount detection apparatus and a positional deviation amount detection method using a predetermined positional deviation amount detection mark to improve the detection accuracy of the positional deviation amount between the reference color mark and the color mark. It is another object of the present invention to provide a positional deviation amount detection program.

The positional deviation amount detection device according to the present invention includes a belt member that is a print medium conveyance belt or an intermediate transfer belt in an electrophotographic color image forming apparatus, an image position related to a specific color, and an image related to a color other than the specific color. An image forming means for forming an image of a position deviation detection mark on the belt member for detecting the position deviation amount with respect to the position. The first misregistration detection mark and the second misregistration detection mark that are imaged and are oblique lines whose inclinations with respect to the running direction of the belt member are opposite to each other, and the running direction of the belt member reading means for reading a third positional shift detection mark a straight line mark orthogonal, the reading from the results read in Step, the first positional shift detection mark and the third position A first interval, which is an interval with respect to the running direction of the belt member, with respect to a deviation detection mark, and a running direction of the belt member with the second positional deviation detection mark and the third positional deviation detection mark. And a calculation procedure for calculating the positional deviation amount based on a second interval which is an interval .

  Further, in one form of the positional deviation amount detection device according to the present invention, when the positional deviation detection mark has a certain width with respect to the running direction of the belt member, the calculation means detects the reading means. The distance between the belt member in the running direction is calculated using the edge position of the first half and the edge position of the second half of the misregistration detection mark.

  In the form of the positional deviation amount detection device according to the present invention, the first positional deviation detection mark or the second positional deviation detection mark is inclined by π / 4 with respect to the traveling direction of the belt member. It is characterized by.

  Therefore, according to the present invention, a positional deviation amount detection device, a positional deviation amount detection method, and a positional deviation amount detection using a predetermined positional deviation amount detection mark, and detecting accuracy of the positional deviation amount between the reference color mark and the color mark is improved. A program can be provided.

  In the present invention, there is provided a positional deviation amount detection device, a positional deviation amount detection method, and a positional deviation amount detection program, which use a predetermined positional deviation amount detection mark to improve the detection accuracy of the positional deviation amount between the reference color mark and the color mark. Can be provided.

The best mode for carrying out the present invention will be described with reference to the drawings.
(Image forming means of misregistration amount detection device according to this embodiment)
(1) Processing Operation of Image Forming Unit of Misregistration Amount Detection Device The image forming unit of the misregistration amount detection device according to this embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a color image forming apparatus as an embodiment of a positional deviation amount detection apparatus 100 according to the present embodiment. The color image forming apparatus is a so-called electrophotographic image forming apparatus.

  The color image forming apparatus according to the present embodiment includes a paper feed tray 1, a paper feed roller 2, a separation roller 3, a recording paper 4, a belt member (hereinafter referred to as a conveyance belt) 5, and image forming units 6BK, 6M, and 6C. , 6Y, driving roller 7, driven roller 8, photosensitive drums 9BK, 9M, 9C, 9Y, chargers 10BK, 10M, 10C, 10Y, exposure unit 11, developing units 12BK, 12M, 12C, 12Y, static eliminator 13BK, 13M, 13C, and 13Y, transfer units 15BK, 15M, 15C, and 15Y, a fixing unit 16, and sensors 17, 18, and 19. Reference numerals 14BK, 14M, 14C, and 14Y denote laser beams that are exposure beams of the respective image colors.

  As shown in FIG. 1, the color image forming apparatus according to the present embodiment includes black as a reference color and magenta, cyan, and yellow as other colors along a conveyor belt 5 that is an endless moving device. The image forming units 6BK, 6M, 6C, and 6Y that form the images of the respective colors are arranged. That is, along the transport belt 5 that transports the paper (recording paper) 4 separated and fed by the paper feed roller 2 and the separation roller 3 from the paper feed tray 1, the transport belt 5 is sequentially transported from the upstream side in the transport direction. A plurality of image forming units 6BK, 6M, 6C, and 6Y are arranged.

  The plurality of image forming units 6BK, 6M, 6C, and 6Y have the same internal configuration except that the color of the toner forming the image is different. Therefore, in the following description, each component of the image forming unit 6BK will be specifically described. Since the other image forming units 6M, 6C, and 6Y have the same processing operation as the image forming unit 6BK, the image forming unit 6M. , 6C, 6Y will not be described.

  The conveyor belt 5 is an endless belt wound around a driving roller 7 and a driven roller 8 that are rotationally driven. The driving roller 7 is driven to rotate by a driving motor, and the driving motor, the driving roller 7 and the driven roller 8 function as a driving device that moves the conveying belt 5 that is an endless moving device.

  At the time of image formation, the sheets 4 stored in the sheet feeding tray 1 are sent out in order from the uppermost one, and the first image forming unit 6BK is transported by the transport belt 5 that is attracted to and rotated by the transport belt 5 by electrostatic attraction. The black toner image is transferred here.

  The image forming unit 6BK includes a photosensitive drum 9BK as a photosensitive member, a charger 10BK disposed around the photosensitive drum 9BK, an exposure unit 11, a developing unit 12BK, a photosensitive cleaner, a static eliminator 13BK, and the like. Yes. The exposure device 11 is configured to irradiate laser beams 14BK, 14M, 14C, and 14Y that are exposure beams corresponding to image colors formed by the image forming units 6BK, 6M, 6C, and 6Y.

  Here, the exposure unit 11 will be described with reference to FIG. FIG. 2 is a view showing the inside of the exposure unit 11. Laser beams 14BK, 14M, 14C, and 14Y that are exposure beams for the respective image colors are emitted from respective laser diodes 21BK, 21M, 21C, and 21Y that are light sources. The irradiated laser beams 14BK, 14M, 14C, and 14Y pass through the optical systems 22BK, 22M, 22C, and 22Y by the reflecting mirror 20, and the optical paths are adjusted, and then to the surfaces of the photosensitive drums 9BK, 9M, 9C, and 9Y. Is scanned. The reflecting mirror 20 is a hexahedral polygon mirror, and can rotate the exposure beam for one line in the main scanning direction per one polygon mirror surface by rotating. Further, the scanning is performed with one polygon mirror for the four laser diodes of the light source.

  The exposure to four different photosensitive drums is simultaneously performed by scanning the laser beam 14BK and 14M and the laser beam 14C and 14Y into two exposure beams for each of the colors and using the opposed reflecting surface of the polygon mirror. It is possible. The optical system 22 includes an f-θ lens that aligns reflected light at equal intervals and a deflection mirror that deflects laser light.

  At the time of image formation, the outer peripheral surface of the photosensitive drum 9BK is uniformly charged by the charger 10BK in the dark, and then exposed by the laser beam 14BK corresponding to the black image from the exposure device 11, thereby forming an electrostatic latent image. It is formed. The developing device 12BK visualizes the electrostatic latent image with black toner, thereby forming a black toner image on the photosensitive drum 9BK.

  This toner image is transferred onto the sheet 4 by the action of the transfer unit 15BK at a position (transfer position) where the photosensitive drum 9BK and the sheet 4 on the transport belt 5 are in contact with each other. By this transfer, an image of black toner is formed on the paper 4.

  As described above, the sheet 4 on which the black toner image is transferred by the image forming unit 6BK is conveyed to the next image forming unit 6M by the conveying belt 5. In the image forming unit 6M, a magenta toner image is formed on the photosensitive drum 9M by a process similar to the image forming process in the image forming unit 6BK, and the toner image is superimposed on the black image formed on the paper 4. And is transcribed.

  Further, the sheet 4 is conveyed to the next image forming units 6C and 6Y, and a cyan toner image formed on the photoconductive drum 9C and a yellow toner formed on the photoconductive drum 9Y by the same operation. An image is superimposed and transferred on the paper 4. Thus, a full-color image is formed on the paper 4. The paper 4 on which the full-color superimposed image is formed is peeled off from the conveying belt 5 and the image is fixed by the fixing device 16, and then discharged to the outside of the image forming apparatus.

  Here, in the color image forming apparatus including the misregistration amount detection apparatus 100 according to the present embodiment, the toner images of the respective colors do not overlap at the positions of the reference colors that should originally overlap, and misregistration occurs between the colors. There is a case. As described above, when a misregistration occurs between the colors, it is necessary to correct the misregistration of the toner images of the respective colors. In this embodiment, the misregistration correction is performed with respect to the black image position. , Cyan, and yellow are performed in the form of matching the image positions. It should be noted that the correction may be made with the image position of the other color as a reference.

(2) Configuration of Misregistration Detection Pattern Next, the configuration of the misregistration detection pattern will be described with reference to FIG. FIG. 3 is a diagram showing an example of a misregistration detection pattern according to the present embodiment. The misregistration detection pattern is composed of four colors of black, magenta, cyan, and yellow, and is a straight line orthogonal to the first misregistration detection mark (25BK_S1, 25M_S1, 25C_S1, 25Y_S1) that is a diagonal line mark. A total of eight of the third misregistration detection marks (25BK_Y1, 25M_Y1, 25C_Y1, 25Y_Y1), which are marks, constitute one set, and second misregistration detection marks (25BK_S2, 25M_S2, 25C_S2) which are hatched marks 25Y_S2) and the third misregistration detection marks (25BK_Y2, 25M_Y2, 25C_Y2, 25Y_Y2). Then, a set of misregistration detection patterns is configured by combining them.

  Here, the first misregistration detection mark and the second misregistration detection mark are oblique marks in which the inclination of the transport body 5 with respect to the transport direction is reversed. In the present embodiment, the first misregistration detection mark is inclined by π / 4 clockwise with respect to the transport direction of the transport body 5, and the second misalignment detection mark is the transport body 5. Is inclined counterclockwise by π / 4, but the inclination of the carrier 5 with respect to the conveyance direction with respect to the first misregistration detection mark and the second misregistration detection mark is π It is not limited to / 4.

  Further, the set period 38 of the misregistration detection pattern in the carrying direction is 1/3 of the circumference of the photosensitive drums 9BK, 9M, 9C, 9Y and 1/2 of the driving roller 7. May be. By doing so, three sets of misregistration detection patterns are formed over one cycle of the photosensitive drum 9, and the misregistration amount due to rotation irregularities of the photosensitive drum 9 is averaged by averaging the misregistration amounts. Variations can be offset. The same applies to the drive roller 7.

  Further, when 24 sets are formed as a set of misregistration detection patterns in the conveyance direction, the length 40 of the misregistration detection pattern set is equal to the circumferential length of the conveyance belt 5. Detection errors due to thickness unevenness and the like can be offset.

  Of the 24 sets constituting one set of misregistration detection patterns shown in FIG. 3, the first 12 sets are only sets including the first misregistration detection marks, and the second 12 sets are the second positions. Only a set including a deviation detection mark is included. The period 39 in the conveying direction of the first 12 sets and the latter 12 sets is equal, and the period 39 may be equal to 4 periods of the photosensitive drum 9 or 6 periods of the driving roller 7.

  As described above, the set including the first misregistration detection mark and the set including the second misregistration detection mark are continuously formed in one cycle or more of the photosensitive drum 9 and the driving roller 7. Thus, the rotation unevenness can be offset in each set.

  Here, in the misregistration amount detection apparatus 100 according to the present embodiment, misregistration detection marks that are black, magenta, cyan, and yellow toner images are the same as in the process of forming a color image on the paper 4. It is formed on the conveyor belt 5 by a process. In addition, each of the image forming units 6BK, 6M, 6C, and 6Y is an image forming unit in the present embodiment.

  In the present embodiment, the conveying belt 5 may be an intermediate transfer belt. In that case, the image forming means forms an image of the position deviation detection mark on the intermediate transfer belt.

(Reading means of misregistration amount detection device)
(1) Outline of Reading Unit The configuration and operation of a sensor that is a reading unit of the positional deviation amount detection apparatus 100 according to the present embodiment will be described with reference to FIGS. 4 and 5. 4 shows an enlarged view of the sensor 17 (18, 19), and FIG. 5 shows the sensor 17 (18, 19) and its peripheral portion.

  The sensor 17 (18, 19) includes a light emitting unit 23 and a light receiving unit 24. Irradiation light is emitted from the light emitting unit 23 to the misregistration detection mark 25 formed on the conveyor belt 5, and the reflected light is received by the light receiving unit 24, so that the sensor 17 (18, 19) detects misregistration. The mark 25 is detected.

  Further, as shown in FIG. 5, the sensors 17 (18, 19) are provided on the downstream side of the image forming unit 6 Y so as to face the conveyance belt 5, and extend along a direction perpendicular to the conveyance direction of the paper 4. Are supported on the same substrate.

(2) Detection Principle of Misregistration Detection Mark The detection principle of the misregistration detection mark will be described with reference to FIG. FIG. 6 is a diagram illustrating the detection principle of the misregistration detection mark. In FIG. 6, the detection result of the reflected light received by the light receiving unit 24 is 31, the detection intensity of the diffuse reflected light received by the light receiving unit 24 is 32, and the detection intensity of the regular reflected light received by the light receiving unit 24 is 33. Show.

  The detection result 31 of the reflected light received by the light receiving unit 24 is obtained by adding the detection intensity 32 of the diffuse reflected light received by the light receiving unit 24 and the detection intensity 33 of the regular reflected light received by the light receiving unit 24. . Further, the vertical axis 34 of the graph in FIG. 6 indicates the light reception intensity of the light receiving unit 24, and the horizontal axis 35 indicates the time.

  Here, the specularly reflected light is the reflected light reflected to the opposite side of the incident direction at the same angle as the incident angle of the irradiated light (that is, the reflected light having a reflection angle of π-θ where the incident angle is θ). In other words, diffuse reflected light refers to reflected light other than regular reflected light.

  Then, the sensors 17 (18, 19) have positions 37BK_1, 37BK_2, 37M_1 (37C_1, 37Y_1), 37M_2 (37C_2, 37Y_2) where the predetermined threshold value 36 and the detection result 31 of the reflected light received by the light receiving unit 24 intersect. ), It is determined that the edge of the misregistration detection mark 25 has been detected. In the present embodiment, the midpoint of two edges detected from each misregistration detection mark 25 (for example, the midpoint between 37BK_1 and 37BK_2) is determined as the image position. The edge 37BK_1, 37BK_2, 37M_1 (37C_1, 37Y_1), 37M_2 (37C_2, 37Y_2) detected from the mark 25 may be determined as the image position.

  Further, in order to improve the S / N ratio (ratio between the intensity of the signal to be detected and the intensity of the noise) at the time of detecting the color misregistration detection mark, the line width 29 in the transport direction of the misregistration detection mark is used. Is substantially the same as the spot diameter 27 of the irradiation light. Further, if the diffusely reflected light reflected from the two marks is received simultaneously, the marks cannot be detected normally, and therefore the position detection mark interval 30 is larger than the spot diameter 28 of the diffusely reflected light. Like that.

  Here, generally, the diffusely reflected light is less reflected on the conveyance belt 5 and the black misregistration detection mark 25 but reflected on the misregistration detection mark 25 of the color (magenta, cyan, yellow). Has the property of Further, the specularly reflected light has a property that it is strongly reflected on the conveyor belt 5 and not reflected on the misregistration detection mark 25 regardless of the color.

  Therefore, consider a case where the alignment between the light emitting unit 23 and the light receiving unit 24 is shifted due to mechanical tolerances, attachment errors, or the like. As shown in FIG. 6, with respect to the color misregistration detection mark 25, the position where the specular reflected light is minimized and the position where the diffuse reflected light is maximized are shifted due to the above properties of the diffuse reflected light. There is a difference between the position calculated from the detection result 31 of the reflected light received by the unit 24 and its actual position.

  On the other hand, for the black misregistration detection mark, the position of the misregistration detection mark can be specified based only on the detection intensity 33 of the specular reflection light, so the position calculated from the actual mark position and the detection result. Matches. That is, an error (41_Y, 41_S described later) occurs in the detection position of the color misregistration detection mark 25, and the misregistration amount cannot be accurately detected. A mechanism for reducing the detection error of the color misregistration detection mark in the misregistration amount detection apparatus according to the present embodiment will be described below.

(Calculation means of misregistration amount detection apparatus according to this embodiment)
(1) Principle of Reducing Misalignment Detection Error The principle of reducing misalignment detection error using the misalignment detection mark according to the present embodiment will be described with reference to FIG. FIG. 7 is a diagram for explaining the principle by which the sensor 17 (18, 19) detects the amount of misalignment from the misalignment detection mark 25. FIG.

  In FIG. 7, as an example, the amount of misregistration is calculated from the black and magenta misregistration detection marks. By replacing the magenta misregistration detection marks with cyan and yellow misregistration detection marks, a black image is obtained. The misregistration amount for cyan and yellow images with reference to can be calculated in the same manner as for magenta.

  FIG. 7 shows the sensor 17, the first misregistration detection mark 25BK_S1 related to black, the first misregistration detection mark 25M_S1 related to magenta, the second misregistration detection mark 25BK_S2 related to black, and the magenta. A second misregistration detection mark 25M_S2, a third misregistration detection mark 25BK_Y1, 25BK_Y2 related to black, and a third misregistration detection mark 25M_Y1, 25M_Y2 related to magenta are illustrated.

  Reference numeral 42BK_1 denotes an interval between the black misregistration detection marks 25BK_Y1 and 25BK_S1, and 42BK_2 denotes an interval between the black misregistration detection marks 25BK_Y2 and 25BK_S2. Further, 42M_1 indicates an interval between the misalignment detection marks 25M_Y1 and 25M_S1 related to magenta, and 42M_2 indicates an interval between the misalignment detection marks 25M_Y2 and 25M_S2 related to magenta.

  Here, the position of each misregistration detection mark necessary for calculating the interval between the misregistration detection marks 25 is the midpoint between the first half edge and the second half edge of each detection mark detected by the sensor 17. Detect as. However, the position of the position detection mark may be in the form of the edge detection position of the first half part or the second half part.

Next, the displacement amounts 43D_1 and 43D_2 in the direction orthogonal to the transport direction calculated from the respective set of displacement detection marks are the first displacement detection mark 25M_S1 related to magenta and the second displacement detection mark 25M_S1 related to magenta. Considering that the absolute value of the angle of the misregistration detection mark 25M_S2 with respect to the transport direction is π / 4,
43D_1 = 42BK_1-42M_1,
43D_2 = 42M_2-42BK_2
It can be expressed as.

  Here, since it is necessary to consider the detection error due to the diffuse reflection light described above when calculating the amount of misalignment, FIG. 7 shows the detection error 41_Y of the third misregistration detection mark related to magenta and the magenta related error. A detection error 41_S of the first misregistration detection mark and the second misregistration detection mark is illustrated. For 41_S, the detection error in the first misregistration detection mark and the detection error in the second misregistration detection mark are assumed to have the same magnitude.

Then, since 42M_1 and 42M_2 are calculated from the detection results of the sensor 17, the positional shift amounts 43D_1 ′ and 43D_2 ′ in the direction orthogonal to the transport direction in consideration of the detection error due to the diffuse reflected light are
43D_1 '= 42BK_1- (42M_1 + 41_Y + 41_S),
43D_2 '= (42M_2 + 41_Y + 41_S) -42BK_2
It can be expressed as.

Since the displacement 43D in the direction perpendicular to the conveyance direction of the magenta image with respect to the black image is represented by an average value of 43D_1 ′ and 43D_2 ′,
43D = (43D_1 '+ 43D_2') / 2
= {42BK_1− (42M_1 + 41_Y + 41_S) + (42M_2 + 41_Y + 41_S) −42BK_2} / 2
= {42BK_1-42M_1 + (42M_2-42BK_2)} / 2
= (43D_1 + 43D_2) / 2
Thus, in calculating the positional deviation amount 43D, the detection errors 41_Y and 41_S due to the diffuse reflected light are canceled out. Thereby, it can be said that the detection accuracy of the displacement 43D in the direction orthogonal to the magenta transport direction is improved.

(2) Calculation means of position deviation amount detection apparatus according to this embodiment Next, the configuration and operation of the calculation means of the position deviation amount detection apparatus according to this embodiment will be described with reference to FIG. FIG. 8 is a diagram showing the configuration of the calculation means of the positional deviation amount detection apparatus according to this embodiment.

  The calculation means according to the present embodiment includes an amplifier 44, a filter 45, an A / D conversion unit (Analog / Digital conversion unit) 46, a sampling control unit 47, a FIFO memory (First In First Out memory) 48, and an I / O port. (Input / Output port) 49, data bus 50, CPU (Central Processing Unit) 51, RAM (Random Access Memory) 52, ROM (Read-Only Memory) 53, and light emission amount control unit 54.

  The reflected light signal received by the light receiving unit 24 is amplified by the amplifier 44. Then, only the signal component for detecting the misregistration detection mark is extracted from the amplified signal using the filter 45. Next, the reflected light signal is converted from analog data to digital data by the A / D converter 46. Sampling of data accompanying this A / D conversion is controlled by the sampling control unit 47, and the sampled signal is stored in the FIFO memory 48.

  After the detection of the set of misregistration detection marks 25 composed of four colors of black, magenta, cyan, and yellow is completed, the data stored in the FIFO memory 48 is transmitted via the I / O port 49 and the data bus 50. Are loaded into the RAM 52. Then, the CPU 51 performs arithmetic processing for calculating the above-described positional deviation amount on the data loaded in the RAM 52.

  The ROM 53 stores various programs for controlling the positional deviation amount detection apparatus according to the present embodiment, including the above-described program for calculating the positional deviation amount. Further, the CPU 51 monitors the detection signal from the light receiving unit 24 at an appropriate timing, and the light emission amount control unit 54 emits light so that it can be reliably detected even if the conveyance belt 5 and the light emitting unit 23 are deteriorated. The amount is controlled so that the level of the light receiving signal from the light receiving unit 24 is always constant. Thus, the CPU 51 and the ROM 53 function as control means for controlling the operation of the entire misregistration amount detection apparatus according to the present embodiment.

(Processing procedure of misregistration amount calculation apparatus according to this embodiment)
The operation process of the positional deviation amount detection apparatus according to the present embodiment will be described with reference to FIG. FIG. 9 is a flowchart illustrating a processing procedure of the positional deviation amount detection apparatus according to the present embodiment.

  In S1, the misregistration amount detection device 100 starts processing. In S2, the image forming units 6BK, 6M, 6C, and 6Y, which are image forming means, form the positional deviation detection pattern according to the present embodiment shown in FIG. On the transport belt 5 moving in the transport direction, first, the image forming unit 6BK forms a black toner image, then the image forming unit 6M forms a magenta toner image, and then the image forming unit 6C. Forms a cyan toner image, and finally, the image forming unit 6Y forms a yellow toner image.

  In S <b> 3, the sensors 17, 18, and 19 serving as reading units read the misregistration detection marks formed on the transport belt 5. Specifically, the light emission unit 23 irradiates the misalignment detection mark 25 formed on the conveyor belt 5 with the light emitting unit 23 and the light receiving unit 24 receives the reflected light. To detect. Since the operations of the sensors 18 and 19 and the processing for the signals received by the sensors 18 and 19 are the same as those for the sensor 17, only matters relating to the sensor 17 will be described below.

  Further, the signal received by the sensor 17 in S3 is temporarily stored in the FIFO memory 48 via the amplifier 44, the filter 45, and the A / D converter 46.

If the sensor 17 detects one set of misregistration detection patterns (consisting of eight misregistration detection marks) in S4 (YES in S4), it is stored in the FIFO memory 48 in S5. The received light signal is stored in the RAM 52 via the I / O port 49 and the data bus 50.
If the sensor 17 has not detected one set of misregistration detection patterns in S4 (NO in S4), the sensor 17 continues to read misregistration detection marks in S3.

If the sensor 17 reads all the misregistration detection marks shown in FIG. 3 in S6 and all the signals received by the sensor 17 are stored in the RAM 52 (YES in S6), the sensor 17 performs in S7. The process for reading the positional deviation detection pattern ends.
If the sensor 17 has not finished reading all the misregistration detection marks shown in FIG. 3 in S6 (NO in S6), the sensor 17 continues to read the misregistration detection pattern in S3. .

  In S <b> 8, the CPU 51 stores the position information of the position shift detection pattern (the first 12 sets in FIG. 3) that is stored in the RAM 52 and includes the first position shift detection mark and the third position shift detection mark. By using this, a displacement amount 43D_1 ′ for each color of magenta, cyan, and yellow is calculated. In the case of magenta, 43D_1 ′ (= 42BK_1− (42M_1 + 41_Y + 41_S) in FIG. 7) is calculated for each set for the black and magenta misregistration detection marks 25 included in the first 12 sets in FIG. The average value is calculated. Similar processing is performed for cyan and yellow.

  In S <b> 9, the CPU 51 stores the positional information of the positional deviation detection pattern (the latter 12 sets in FIG. 3) that is stored in the RAM 52 and is composed of the second positional deviation detection mark and the third positional deviation detection mark. By using this, a positional shift amount 43D_2 ′ for each color of magenta, cyan, and yellow is calculated. In the case of magenta, 43D_2 ′ (= (42M_2 + 41_Y + 41_S) −42BK_2) in FIG. 7 is calculated for each set of black and magenta misregistration detection marks 25 included in the latter half 12 sets in FIG. The average value is calculated. Similar processing is performed for cyan and yellow.

In S10, the CPU 51 calculates an average value of the above-described positional deviation amount 43D_1 ′ and positional deviation amount 43D_2 ′ for each of magenta, cyan, and yellow, and uses these values as the conveyance direction of the image position of each color relative to the image position of the reference color black. It is assumed that the amount of displacement 43D is perpendicular to the direction.
In S11, the CPU 51 stores the displacement amount 43D in the direction orthogonal to the transport direction calculated in S10 in the RAM 52, and in S12, the processing of the displacement amount detection device according to the present embodiment ends.

  By performing such processing, it is possible to provide a misregistration amount detection device that uses a predetermined misregistration detection mark to improve the detection accuracy of the misregistration amount between the reference color mark and the color mark.

  Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications are possible within the scope of the gist of the present invention described in the claims.・ Change is possible.

It is a figure which shows the structure of the positional deviation amount detection apparatus which concerns on this Embodiment. It is a figure which shows the inside of the exposure device of the position shift amount detection apparatus which concerns on this Embodiment. It is a figure which shows an example of the pattern for a position shift detection which concerns on this Embodiment. It is the figure which expanded the sensor of the positional deviation amount detection apparatus which concerns on this Embodiment. It is a figure which shows the sensor of the positional deviation amount detection apparatus which concerns on this Embodiment, and its peripheral part. It is a figure which shows the detection principle of the position shift detection mark which concerns on this Embodiment. It is a figure explaining the principle which detects the amount of position shift concerning this embodiment. It is a figure which shows the structure of the calculation means of the positional deviation amount detection apparatus which concerns on this Embodiment. It is a flowchart which shows the process sequence of the position shift amount detection apparatus which concerns on this Embodiment.

Explanation of symbols

100 Position shift amount detection device 5 Conveyor belt 6BK, 6M, 6C, 6Y Image forming unit 17, 18, 19 Sensor 44 Amplifier 45 Filter 46 A / D conversion unit 47 Sampling control unit 48 FIFO memory 49 I / O port 50 Data bus 51 CPU
52 RAM
53 ROM

Claims (7)

Detecting a positional deviation amount between a belt member which is a printing medium conveyance belt or an intermediate transfer belt in an electrophotographic color image forming apparatus and an image position related to a specific color and an image position related to a color other than the specific color An image forming means for forming an image of a position detection mark on the belt member,
A first misregistration detection mark and a second misregistration detection mark which are imaged on the belt member by the imaging means and which are oblique marks whose inclinations with respect to the running direction of the belt member are opposite to each other; Reading means for reading a third misregistration detection mark that is a straight mark perpendicular to the running direction of the belt member;
From the result of reading by the reading means , a first interval that is an interval between the first misalignment detection mark and the third misalignment detection mark in the running direction of the belt member, and the second Other than the specific color from the first interval according to the specific color based on a second interval that is an interval between the misalignment detection mark and the third misregistration detection mark in the running direction of the belt member. A first difference value obtained by subtracting the first interval relating to the color of the second color, and a second difference obtained by subtracting the second interval relating to the specific color from the second interval relating to a color other than the specific color. And a calculating means for calculating the amount of positional deviation from the average value of the values . When the positional deviation detection mark has a certain width with respect to the running direction of the belt member,
The calculating means calculates an interval in the running direction of the belt member by using an edge position of a first half portion and an edge position of a second half portion of the misregistration detection mark detected by the reading means. The positional deviation amount detection apparatus according to claim 1 . The first positional shift detection mark or the second positional shift detection mark is located according to claim 1 or 2, characterized in that it is [pi / 4 inclined with respect to the running direction of the belt member Deviation detection device. Detecting a positional deviation amount between a belt member which is a printing medium conveyance belt or an intermediate transfer belt in an electrophotographic color image forming apparatus and an image position related to a specific color and an image position related to a color other than the specific color An image forming procedure for forming an image of a position shift detection mark on the belt member, and a position shift amount detection method of a position shift amount detection device comprising:
A first misregistration detection mark and a second misregistration detection mark which are imaged on the belt member by the imaging procedure and which are oblique marks whose inclinations with respect to the running direction of the belt member are opposite to each other; A reading procedure for reading a third misregistration detection mark that is a straight mark perpendicular to the running direction of the belt member;
From the result of reading in the reading procedure, a first interval that is an interval between the first misalignment detection mark and the third misalignment detection mark in the running direction of the belt member, and the second Other than the specific color from the first interval according to the specific color based on a second interval that is an interval between the misalignment detection mark and the third misregistration detection mark in the running direction of the belt member. A first difference value obtained by subtracting the first interval relating to the color of the second color, and a second difference obtained by subtracting the second interval relating to the specific color from the second interval relating to a color other than the specific color. And a calculation procedure for calculating the positional deviation amount from an average value thereof. When the positional deviation detection mark has a certain width with respect to the running direction of the belt member,
The calculation procedure calculates an interval in the running direction of the belt member using an edge position of a first half portion and an edge position of a second half portion of the misregistration detection mark detected by the reading procedure. The positional deviation amount detection method according to claim 4 . 6. The position according to claim 4, wherein the first misregistration detection mark or the second misregistration detection mark is inclined by π / 4 with respect to a traveling direction of the belt member. Deviation detection method. A misregistration amount detection program for causing a computer to execute the misregistration detection method according to any one of claims 4 to 6 .

Images